Figure 1. DMS-EB-RMS Schematic Diagram
PRODUCT OVERVIEW
Description: The DMS-EB-RMS board allows the true rms value of ac signals to be displayed on
5V-powered DMS-30PC/LCD digital voltmeters. The meter/board combination has an input range of
0-750Vac with ±2V meters (1Vac resolution) or 0-199.9Vac with ±200mV meters (0.1Vac resolution).
A built-in screw-terminal block reliably interfaces signal and power connections. The DMS-EB-RMS
now accommodates user-installed modifi cations such as input-scaling resistors and isolated +5V dc/dc
converters.
Power and Safety Precautions: The DMS-EB-RMS’s AC HI and AC LOW inputs are not electri-
cally isolated from its 5V supply (AC LOW is connected directly to 5V RETURN). When measuring any
input signal which is derived from ac power mains, a dedicated (i.e., it only powers the DMS-EB-RMS),
transformer-isolated +5V supply, with a minimum 1kV breakdown rating, must be used to power the
DMS-EB-RMS board/meter combination. When measuring ac power mains inputs, never connect the
DMS-EB-RMS’s 5V RETURN to chassis/earth ground anywhere in the system. Failing to follow these
instructions could defeat any safety grounding and will place the system +5V power supply, and all its
associated circuitry, at dangerously elevated ac-line potentials. In many applications, the MS-EB-RMS
installation is required to meet electrical code requirements. To ensure safe operation, the DMS-EB-
RMS board should only be installed and serviced by technically qualifi ed personnel. See DMS
Application Note 11 for more details.
FEATURES
Displays true rms values of ac inputs
±0.5% accuracy for DMS-30PC-0 or DMS-
30LCD-0-5
±2% accuracy for DMS-30PC-1 or DMS-
30LCD-1-5
Also works with DMS-40PC/LCD meters (see Ap
Note 11)
(–) INPUT LO
(+) INPUT HI
REF. OUT
REF. IN
156
3
+5V 5V Return
TB1
CAV
OUT
+V
S
COM
–V
S
CF
V
IN
CC
V
OUT
LV
OSC
V+
CAP–
GND
CAP+
BOOST
SG1
SG2
SG3
5V RETURN
DP3
DP2
DP1
+5V SUPPLY
C5
2.2μF
+
+
R1
988k
R2
988k
R3
1.98k
+
C2
10μF
C1 100μF
+
1
2
3
4
5
6
7
8
5
6
7
81
2
3
4
U1 U2
AC HI
3
4
5
6
1
2
SG4
J1
12
11
8
7
10
9
JP1
J6
GND 2
13
U3
PS1
1
2
3
4
C4
2.2μF
J4 J5
AC LOW
Note: Components are user-supplied
and not part of the standard product.
DC/DC
–V
+V +V
IN
–V
OUT
V
IN
V
OUT
www.murata-ps.com
www.murata-ps.com/support
For full details go to
www.murata-ps.com/rohs
DMS-EB-RMS
AC-to-RMS Converter Application Board for DMS-30PC/LCD Meters
MPM_DMS-EB-RMS.C01 Page 1 of 2
Functional Specifi cations
(TA = +25°C, VCC = +5V)
Ordering Information
DMS-EB-RMS-C AC-to-RMS conversion board
DMS-BZL1-C Bezel assembly
DMS-BZL2-C Bezel assembly with sealing gasket
Figure 2. DMS-EB-RMS Board
Vac Measurement Range:
±200mV meters 0 to 199.9Vac
±2V meters 0 to 750Vac
Conversion Accuracy:
0-200Vac ±0.5%
0-750Vac ±2%
Crest Factors
3, maximum
Input Frequency Range
40Hz to 2kHz
Primary Operating Power
+5V (±5%)
Current Consumption (Board only)
+0.5mA typ., +1mA max.
Operating Temperature Range
0 to +60°C
Storage Temperature Range
–20 to +75°C
Humidity
0 to 95%, non-condensing
Dimensions
2.02" (51.31mm)W x 0.83" (21.08mm)H
www.murata-ps.com/support
Murata Power Solutions, Inc. makes no representation that the use of its products in the circuits described herein, or the use of other
technical information contained herein, will not infringe upon existing or future patent rights. The descriptions contained herein do not imply
the granting of licenses to make, use, or sell equipment constructed in accordance therewith. Specifi cations are subject to change without
notice. © 2015 Murata Power Solutions, Inc.
Murata Power Solutions, Inc.
11 Cabot Boulevard, Mansfi eld, MA 02048-1151 U.S.A.
ISO 9001 and 14001 REGISTERED
This product is subject to the following operating requirements
and the Life and Safety Critical Application Sales Policy:
Refer to: http://www.murata-ps.com/requirements/
DMS-EB-RMS
AC-to-RMS Converter Application Board for DMS-30PC/LCD Meters
MPM_DMS-EB-RMS.C01 Page 2 of 2
